So "TRMP3" is a type of calcium ion channel that regulates the flow of CA+ ions into the cells? If I have an autoantibody to the N-Type CA+ Channel, would these be comparable (meaning N-type is one type and TRMP3 is simply another type)?
N-type channels and TRPM3 are both ion channel proteins that allow calcium into the cell, though they function very differently.
N-type channels are called voltage gated because the protein is stimulated to change shape and create an opening to allow calcium ions through in response to a change in voltage across the cell membrane.
Most of the well studied calcium channel proteins (and there are a number of different types) are voltage gated. These are the type of channels that are active in the heart and in neurons and can mediate things like muscle contraction and release of neurotransmitters.
TRPM3 proteins are ligand gated, ie the shape change that opens the channel is stimulated by binding of a small molecule (the ligand), rather than by electrical changes in the cell membrane.
Many of the TRP family of molecules are sensory receptors with TRPM3 being sensitive to heat. It is also linked to insulin release. Less is known about them than the voltage gated type.
How would someone know which systems are linked to a particular ion channel (or autoantibody) or is this unknown at this time?
Scientists devise incredibly complicated experiments to work this out and trust me you don't want to go delving into the detail. It is bewilderingly complex.
You don't need to know this detail, you just need to know that the cell has complex mechanisms for distinguishing between the different types of calcium channels and responding accordingly.
As for working out the clinical effects of a calcium channel autoantibody, well this is where you need a good physician.